A ceramicizable aerogel composite material with excellent thermal protection performance and a preparation method and application thereof

Abstract

The application provides an aerogel composite material capable of in-situ ceramization and having excellent heat protection performance, and a preparation method and application thereof, and belongs to the field of composite materials.The aerogel composite material is composed of a fiber felt coated with a ceramic precursor and a resin, and the ceramic precursor is a SiC ceramic precursor and a ZrC ceramic precursor.The aerogel composite material prepared by the application has excellent ablation resistance and excellent heat insulation performance in a severe thermal environment.The aerogel composite material has a wide application prospect in a lightweight heat protection system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of composite materials, and particularly relates to an aerogel composite material capable of in-situ ceramming and having excellent thermal protection performance, and a preparation method and application thereof. BACKGROUND

[0002] When a spacecraft enters the atmosphere, it will generate a serious thermal load, at which time a thermal protection system (TPS) is needed to act as a thermal barrier to protect the spacecraft from the thermal load, thereby ensuring flight safety. Since the 1990s, the development of deep space exploration, space-air return and other tasks has put forward higher requirements for the heat insulation performance and lightweight of TPS. For this reason, NASA has developed AVCOAT, phenolic impregnated carbon ablation body (PICA) and other lightweight TPS, and successfully applied them to Apollo spacecraft and Stardust. However, these traditional lightweight TPS have low mechanical strength, poor resistance to high-speed hot gas flow scouring, are prone to serious oxidation and mechanical ablation, and cannot meet the increasingly stringent service environment. Therefore, a new generation of lightweight TPS needs to be designed to provide excellent thermal protection capability while taking into account the lightweight characteristics.

[0003] In recent years, many researchers have been working on designing the next generation of lightweight TPS. The performance of lightweight TPS mainly depends on the resin matrix and three-dimensional skeleton reinforcing structure. At present, Poly(dimethyl-diphenyl-imide)siloxane / phenolic-based double network hybrid resin coatings for ablation thermal protection reports a silicon / phenolic hybrid resin with excellent ablation resistance. As the most widely used lightweight TPS, the traditional PICA uses short carbon fibers as the reinforcing phase, but its intrinsic brittleness will result in poor formability and low mechanical strength of the material. Therefore, researchers have focused on continuous carbon fiber needle felt, which has the advantages of lightweight, low thermal expansion and high mechanical strength, as a reinforcing material, and the aerogel composite material prepared by using phenolic resin (PR) as the matrix can effectively avoid splicing, suturing and other processes, which is beneficial to the formation of large-sized parts. However, the carbon fiber itself has weak oxidation resistance and is prone to failure due to severe oxidation under long-time scouring of high-temperature high-speed oxygen-containing hot gas flow, so the ablation resistance of the aerogel composite material obtained at present is poor. Therefore, it is urgent to effectively improve the oxidation resistance of the carbon fiber felt.

[0004] Some beneficial attempts have been reported in the literature. For example, ZrB2, SiO2, SiC, TiO2, etc. are introduced into aerogel composites, which improves the oxidation resistance of aerogel composites to some extent and improves the thermal protection performance. However, the introduction of these high-density ceramic particles (for example, the density of ZrB2 is as high as 6 g / cm 3 ) is not conducive to the demand of new spacecraft for TPS weight reduction. At the same time, they have poor interfacial compatibility with fibers and resin particles, and are difficult to disperse uniformly, which is not conducive to the further improvement of the thermal protection performance of aerogel composites. Therefore, how to improve the thermal protection performance as much as possible while ensuring the lightweight of aerogel composites, including improving the thermal conductivity, ablation resistance and thermal insulation performance of aerogel composites, is still a big challenge in the preparation of new lightweight TPS. SUMMARY

[0005] The purpose of the present application is to provide an aerogel composite which can be in-situ ceramized and has excellent thermal protection performance, and a preparation method and application thereof.

[0006] The present application provides a fiber felt aerogel composite, the raw materials of which include a ceramic precursor coated fiber felt and a resin, and the ceramic precursor is SiC ceramic precursor and ZrC ceramic precursor.

[0007] Further, the resin is phenolic resin;

[0008] The fiber felt is high-silica fiber felt, mullite fiber felt, carbon fiber felt, phenolic fiber felt, aramid fiber felt;

[0009] The SiC ceramic precursor is any one or two or more of polycarbosilane, SiC powder, polysiloxane and polysilazane.

[0010] Further, the fiber felt is carbon fiber felt; and the phenolic resin is organosilicon hybrid phenolic resin;

[0011] The organosilicon hybrid phenolic resin is prepared from AMPS, 3,3',4,4'-diphenyl tetracarboxylic dianhydride, (3-aminopropyl) triethoxysilane and phenolic resin as raw materials;

[0012] The AMPS is prepared from octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane and 1,3-bis(3-aminopropyl) tetramethyl disiloxane as raw materials.

[0013] Further, the preparation method of the AMPS comprises the following steps:

[0014] Mixing octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane and catalyst, and then reacting under inert gas to obtain the product;

[0015] Preferably,

[0016] The catalyst is tetramethylammonium hydroxide;

[0017] And / or, the reaction is carried out at 80-180℃ for 1-8h, and then the temperature is raised to 150-200℃ for 0.5-5h;

[0018] The mass of the catalyst is 0.1%-6% of the total mass of octaphenylcyclotetrasiloxane and octamethylcyclotetrasiloxane;

[0019] The molar ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane and 1,3-bis(3-aminopropyl)tetramethyldisiloxane is (0.5-5):(5-9.5):2, preferably 1.5:8.5:2.

[0020] Further,

[0021] The molar ratio of the amino group in AMPS and the anhydride in 3,3',4,4'-biphenyl tetracarboxylic dianhydride is 1:1:0.5-1.6;

[0022] The (3-aminopropyl)triethoxysilane is 10%-50% mol of the amino content in AMPS.

[0023] Further, the hybrid phenolic resin is prepared by the following method;

[0024] (1) mixing 3,3',4,4'-biphenyl tetracarboxylic dianhydride and AMPS in a solvent and then reacting;

[0025] (2) adding (3-aminopropyl)triethoxysilane and continuing to react to obtain AMPSA;

[0026] (3) reacting AMPSA with a phenolic resin solution to obtain the product;

[0027] Preferably,

[0028] In step (1), the solvent is tetrahydrofuran;

[0029] And / or, in step (1), the reaction temperature is 20-80℃, the reaction time is 0.5-5h, and the mass ratio of the solvent to AMPS is (1-5):1;

[0030] And / or, in step (2), the reaction temperature is 20-80℃, and the reaction time is 0.5-5h;

[0031] And / or, in step (3), the solvent of the phenolic resin solution is ethanol, wherein the mass ratio of the phenolic resin and the ethanol is (0.5-1):1, the temperature of the reaction is 50-110℃, and the time of the reaction is 0.5-2h.

[0032] Further, the method for preparing the ceramic precursor coated fiber felt comprises the following steps:

[0033] 1) after the fiber felt is immersed in the solution of the SiC ceramic precursor, solidification is performed to obtain the fiber felt coated by the SiC ceramic precursor;

[0034] 2) after the carbon fiber coated by the SiC ceramic precursor obtained in step 1) is immersed in the solution of the ZrC ceramic precursor, solidification is performed, and the ceramic precursor coated fiber felt is obtained;

[0035] Or,

[0036] a) after the fiber felt is immersed in the solution of the ZrC ceramic precursor, solidification is performed to obtain the fiber felt coated by the ZrC ceramic precursor;

[0037] b) after the carbon fiber coated by the ZrC ceramic precursor obtained in step a) is immersed in the solution of the SiC ceramic precursor, solidification is performed, and the ceramic precursor coated fiber felt is obtained;

[0038] Preferably,

[0039] The solvent in the solution of the SiC ceramic precursor or the solution of the ZrC ceramic precursor is selected from any one or two or more of benzene, toluene, xylene, tetrahydrofuran, and ethylene glycol;

[0040] The solidification is solidification at 100-300℃ for 0.5-5h in an inert gas;

[0041] The mass concentration of the SiC ceramic precursor in the solution of the SiC ceramic precursor is 0.1%-30%;

[0042] The mass concentration of the ZrC ceramic precursor in the solution of the ZrC ceramic precursor is 0.1%-30%.

[0043] Further,

[0044] The solidification is solidification at 200℃ for 1h in nitrogen;

[0045] The mass concentration of the SiC ceramic precursor in the solution of the SiC ceramic precursor is 3%;

[0046] The mass concentration of the ZrC ceramic precursor in the solution of the ZrC ceramic precursor is 3%.

[0047] The application further provides a method for preparing the fiber felt aerogel composite material.

[0048] 1) mixing the resin with the organic solvent A and the curing agent to obtain a mixed solution, and then performing sol-gel after impregnating the ceramic precursor coated fiber felt with the mixed solution to obtain a wet gel;

[0049] 2) performing solvent replacement on the wet gel obtained in step 1) with the organic solvent B to obtain the fiber felt aerogel composite material.

[0050] Preferably,

[0051] The organic solvent A is selected from any one of ethylene glycol, dimethylbenzene, dimethyl sulfoxide, acetone, ethanol and tetrahydrofuran.

[0052] The organic solvent B is selected from any one of ethanol, tetrahydrofuran, acetone and toluene, and preferably is ethanol; the solvent A and the solvent B are different.

[0053] The curing agent is selected from any one or more of hexamethylenetetramine, thermosetting phenolic resin and paraformaldehyde.

[0054] The sol-gel is sequentially kept at 90-150 DEG C for 0.5-5 h, kept at 90-400 DEG C for 0.5-5 h, and kept at 150-280 DEG C for 0.5-5 h.

[0055] The mass ratio of the resin, the organic solvent A and the curing agent in step 2) is (0.1-5):(0.1-10):(0.01-10).

[0056] More preferably,

[0057] The organic solvent A is ethylene glycol, the organic solvent B is ethanol, the curing agent is hexamethylenetetramine, the mass ratio of the resin, the organic solvent A and the curing agent in step 2) is 1:4:0.15, and the sol-gel is sequentially kept at 120 DEG C for 2 h, kept at 150 DEG C for 2 h, and kept at 180 DEG C for 2 h.

[0058] The application further provides a use of the fiber felt aerogel composite material in preparing thermal protection materials.

[0059] The application provides an in-situ ceramicizable aerogel composite material with excellent thermal protection performance, a preparation method and application thereof, and the aerogel composite material is prepared by sequentially impregnating and curing SiC ceramic precursors and ZrC ceramic precursors on a carbon fiber felt to obtain a carbon fiber felt coated with a SiC-ZrC composite ceramic precursor layer, and then compounding an organic silicon hybrid phenolic resin to obtain a carbon fiber felt reinforced silicon / phenolic hybrid aerogel composite material coated with a ceramic precursor. 3The aerogel composite CPA SiC-ZrC of the application can meet the demand of new spacecraft for TPS weight reduction; the linear ablation rate of the aerogel composite CPA 0-0 of the application is reduced by 66.7%, and the aerogel composite has excellent ablation resistance; the back temperature of the aerogel composite is only 147 DEG C after working for 70s at 1950 DEG C, and the aerogel composite has excellent heat insulation performance in a harsh thermal environment. The experimental results show that the aerogel composite of the application is expected to become a candidate material for lightweight TPS, and can be applied to difficult tasks such as deep space exploration, space-air-ground round trip, near space long flight, etc.

[0060] Obviously, according to the above content of the application, according to the ordinary technical knowledge and common means in the art, other various forms of modification, replacement or change can be made without departing from the above technical idea of the application.

[0061] The above content of the application will be further described in detail through the specific embodiments in the form of examples. However, it should not be understood that the above subject matter of the application is limited to the following examples. Any technology achieved based on the above content of the application belongs to the scope of the application. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 : SiPR prepolymer structural formula

[0063] Figure 2 : Microstructure diagrams of different carbon fibers; a: schematic diagram of the surface of different carbon fibers; b-e: SEM diagrams of the surface of different carbon fibers; f-i: AFM of the surface of different carbon fibers.

[0064] Figure 3 : (a-d) are microstructure diagrams of CPA 0-0 , CPA SiC-0 , CPA 0-ZrC , CPA SiC-ZrC , respectively; (e-h) are nitrogen adsorption and desorption tests of CPA 0-0 , CPA SiC-0 , CPA 0-ZrC , CPA SiC-ZrC , respectively.

[0065] Figure 4 TG thermogravimetric curves of different aerogel composites in air atmosphere.

[0066] Figure 5 : Test results of the infrared thermal imaging instrument heat insulation performance of different aerogel composites at a lower temperature.

[0067] Figure 6 : Heat insulation performance test results of different aerogel composites at 2.5MW / m 2Thermal protection performance in the environment; a~d are CPA 0-0 , CPA SiC-0 , CPA 0-ZrC , CPA SiC-ZrC Optical photos of the ablated surface; e~h are CPA 0-0 , CPA SiC-0 , CPA 0-ZrC , CPA SiC-ZrC Three-dimensional profile of the ablated sample.

[0068] Figure 7 : a: back temperature changes of different aerogel composites during the ablation process; b: XRD patterns of the surface layer of different aerogel composites after ablation; c: schematic diagram of different regions of different aerogel composites after ablation; d~g: CPA in turn 0-0 , CPA SiC-0 , CPA 0-ZrC , CPA SiC-ZrC SEM of the surface layer; h~k: CPA in turn 0-0 , CPA SiC-0 , CPA 0-ZrC , CPA SiC-ZrC SEM of the pyrolytic layer. DETAILED DESCRIPTION

[0069] The raw materials and equipment used in the application are known products, which are obtained by purchasing commercially available products.

[0070] The phenolic resin (PR) is purchased from Henan Zhongfan Dongsheng Company, and the item number is G913.

[0071] Hexamethylenetetramine (HMTA) and octaphenylcyclosiloxane (P4), octamethylcyclotrisiloxane (D4), (3-aminopropyl) triethoxysilane (APTES), 1,3-bis (3-aminopropyl) tetramethyl disiloxane, and tetramethylammonium hydroxide are purchased from Shanghai Aldrin.

[0072] Tetrahydrofuran (THF), dimethylbenzene, anhydrous ethanol (EtOH), and ethylene glycol (EG) are purchased from Shanghai Titan Technology Co., Ltd.

[0073] The carbon fiber felt is purchased from Jiangsu Tianniao High Technology Co., Ltd.

[0074] 3,3',4,4'-Biphenyl tetracarboxylic dianhydride (BPDA).

[0075] ZrC ceramic precursor is purchased from Beijing Forsman, and the item number is 4004019.

[0076] Polycarbosilane (PCS) is purchased from Suzhou Saileifei Ceramic Fiber Co., Ltd., and the PCS molar mass is 1100-1600 g / mol.

[0077] Example 1, Preparation of aerogel composite material of the present application

[0078] I. Experimental method (1) Preparation of CF SiC-ZrC

[0079] 1. Preparation of SiC-coated carbon fiber

[0080] A 3wt% PCS solution in xylene was prepared, i.e. a SiC ceramic precursor solution, and a carbon fiber felt (denoted as CF 0-0 ) was fully immersed in the SiC ceramic precursor solution and cured at 200°C for 1 h to coat the surface of the carbon fiber with a layer of PCS, obtaining PCS-coated carbon fiber, denoted as CF SiC -0.

[0081] 2. Preparation of CF SiC-ZrC

[0082] The CF SiC-0 obtained in step 1 was fully immersed again with a 3wt% ZrC ceramic precursor solution in xylene and cured at 200°C for 1 h in a nitrogen atmosphere to obtain a carbon fiber felt coated with a layer of SiC-ZrC composite ceramic precursor, denoted as CF SiC-ZrC .

[0083] (2) Preparation of organosilicon phenolic hybrid resin SiPR

[0084] AMPS was synthesized by anionic ring-opening polymerization of D4, P4 and 1,3-bis(3- aminopropyl)tetramethyldisiloxane in the presence of tetramethylammonium hydroxide as catalyst. Specifically, 8.5 mol of D4, 1.5 mol of P4, 2 mol of 1,3-bis(3- aminopropyl)tetramethyldisiloxane and tetramethylammonium hydroxide (TMAOH) were added to a three-necked flask and reacted at 120°C for 2.5 h. Then, the temperature of the system was raised to 150°C for 0.5 h, and the catalyst tetramethylammonium hydroxide was decomposed into trimethylamine and methanol. Finally, the system was vacuumed to remove the unreacted monomers, trimethylamine and methanol, obtaining a colorless and transparent viscous liquid, i.e. AMPS. The amount of catalyst tetramethylammonium hydroxide was 0.5wt% of the total mass of P4 and D4, and the molar content of phenyl groups in the synthesized AMPS was 15%.

[0085] A three-neck flask containing BPDA (the molar ratio of amino group in AMPS and acid anhydride in BPDA is 1:1.05) and tetrahydrofuran (THF, the mass ratio of THF and AMPS is 1:1) was added dropwise with 50wt% AMPS THF solution under nitrogen atmosphere, and reacted at 35°C for 2.5h to ensure that the molecular chain was capped with excess acid anhydride. Then, a capping agent APTES (APTES was added in an amount of 20mol% of the amino content in AMPS) was added, and the reaction was continued for 1h to obtain a transparent viscous AMPSA.

[0086] The AMPSA was added to a 50wt% PR ethanol solution (the mass ratio of PR and anhydrous ethanol is 1:1), and reacted at 80°C for 1h. The solvent was removed under vacuum to obtain a light yellow powder, which was a SiPR prepolymer. The structure of the SiPR prepolymer is shown in Figure 1 .

[0087] (III) Preparation of CPA SiC-ZrC

[0088] The SiPR solution was prepared according to the mass ratio of SiPR prepolymer:EG:HMTA=1:4:0.15, and then the CF SiC-ZrC was fully impregnated with the solution. The impregnated fiber felt was subjected to sol-gel at 120°C / 2h+150°C / 2h+180°C / 2h. The obtained wet gel was subjected to EtOH replacement for 3d to obtain a solvent-replaced gel. The solvent-replaced gel was dried at 40°C under normal pressure for 1d to obtain a SiC-ZrC ceramic precursor coated carbon fiber felt reinforced silicon / phenolic hybrid aerogel composite (CPA SiC-ZrC ).

[0089] Comparative Example 1, CPA SiC-0 Aerogel composite preparation

[0090] CF SiC-0 was used instead of CF SiC-ZrC in Example 1, and the rest was the same as Example 1. The obtained aerogel composite was named CPA SiC-0 .

[0091] Comparative Example 2, CPA 0-ZrC Aerogel composite preparation

[0092] The carbon fiber was directly impregnated with 3wt% ZrC ceramic precursor and cured at 200°C for 1h in nitrogen to obtain a 0-ZrC ceramic precursor layer coated carbon fiber felt, which was CF 0-ZrC .

[0093] CF 0-ZrC was used instead of CF SiC-ZrCThe rest is the same as Example 1, and the prepared aerogel composite is named as CPA 0-ZrC .

[0094] Comparative Example 3, CPA SiC-0 Preparation of aerogel composite

[0095] CF 0-0 instead of CF SiC-ZrC in Example 1, and the rest is the same as Example 1, and the prepared aerogel composite is named as CPA 0-0 .

[0096] The following experimental examples demonstrate the beneficial effects of the aerogel composite prepared in the application.

[0097] Experimental Example 1, Microstructure of different carbon fibers in the application

[0098] Firstly, the CF 0-0 , CF SiC-0 , CF 0-ZrC , CF SiC-ZrC carbon fiber mats were characterized by SEM, as shown in Figure 2 b~ Figure 2 e.The fiber surface of CF 0-0 is very smooth ( Figure 2 b), and after coating different ceramic precursor coatings, the surfaces of all the fibers become rough, and the diameters of the fibers increase by 0.3-0.6 μm compared with the original fibers. It is worth noting that the surface coating of CF 0-ZrC cracks ( Figure 2 d, dashed box).

[0099] The Mapping results ( Figure 2 c~ Figure 2 e, embedded graphs) show that Si and Zr elements are uniformly and densely distributed on the fiber surface. Figure 2 f~ Figure 3 i show the AFM results of the fiber surface.

[0100] It can be found that compared with the original fiber, the coated fiber surface has obvious undulations, and the surface roughness also increases significantly, which is consistent with the SEM results.

[0101] Experimental Example 2, Microstructure of aerogel composite in the application

[0102] In order to further explore the pore structure of different aerogel composites, nitrogen adsorption and desorption tests were carried out by a full-automatic physical adsorption instrument, and the results are shown in Figure 3 i~ Figure 3 l and Table 1.

[0103] ​​​According to the IUPAC classification, all aerogel composites show type IV isotherms and H3 hysteresis loops, which indicates that they have similar pore structures. The high relative pressure indicates that the microstructure includes mesopore and macropore structures resulting from capillary condensation. The pore size distribution indicates that the pore size of the aerogel composite prepared by coating carbon fiber felt with different ceramic precursors is obviously different. Among them, the pore size distribution range of CPA Figure 3 i Figure 4 l) is the widest, reaching from 10 nm to 120 nm. This rich pore size distribution is conducive to reducing the overall density of the material while ensuring the blocking of heat transfer. SiC-ZrC

[0104] Table 1 Physical information of different aerogel composites

[0105]

[0106] Note: S BET : BET surface area; S mic : micropore surface area; S meso : desorption cumulative surface area of 1.7-300 nm pore size; V mic : micropore volume; V meso : desorption cumulative volume of 1.7-300 nm pore size; V total : total pore volume calculated at a relative pressure of 0.99; S avg : BJH desorption average pore size (4V / A).

[0107] Experimental Example 3 Mechanical properties and thermal properties of aerogel composites of the present application

[0108] The mechanical properties of CPA SiC-ZrC in xy and z directions were tested using a universal testing machine. The compressive strength of CPA SiC-ZrC in xy direction was 2.5 MPa, and the compressive strength of CPA SiC-ZrC in z direction was 2.5 MPa.

[0109] The aerogel composites were tested by a thermogravimetric analyzer, Figure 5 showing the TG curves of different aerogel composites in air atmosphere. It can be seen that the carbon residue rate of CPA SiC-ZrC at 800℃ in air atmosphere is greatly enhanced, reaching 62%, which is 15% higher than the carbon residue rate of 47% of CPA 0-0 .

[0110] Experimental Example 4 Density and thermal insulation performance of aerogel composites of the present application

[0111] ​The thermal insulation performance of different aerogel composite materials at a low temperature (220℃) was tested using an infrared thermal imager. The results are as follows: Figure 6 As shown, after heating different aerogel composite materials with a thickness of 12 mm on a 220°C hot platform for 10 minutes, the surface temperature of all of them was around 78°C.

[0112] This invention uses a Hot Disk thermal constant analyzer to test the thermal conductivity in the z-direction of different aerogel composites. The experimental results are shown in Table 2. It can be seen that, compared with CPA... 0-0 In comparison, CPA SiC-0 Decreased thermal conductivity, CPA 0-ZrC The thermal conductivity is increased, while CPA SiC-ZrC The thermal conductivity decreased significantly, down to 0.057 W·m. -1 ·K -1 This achieved unexpected technical results.

[0113] Experimental results show that the present invention CPA SiC-ZrC It has extremely low thermal conductivity, which is why CPA SiC-ZrC It offers strong competitiveness as a thermal protection material for extreme thermal environments in the future.

[0114] Table 2. Density and thermal conductivity of different aerogel composite materials

[0115]

[0116] Experimental Example 5: Thermal protection performance of the aerogel composite material of the present invention

[0117] Using 2.5MW / m 2 The oxyacetylene flame simulates the extreme thermal environment that lightweight TPS would experience.

[0118] An approximately 12 mm thick aerogel composite material was exposed to 2.5 MW / m². 2 The linear ablation rate (LAR) and mass ablation rate (MAR) of the aerogel composite were tested after ablation under an oxyacetylene flame for 70 s. The surface morphology of the sample after ablation is shown below. Figure 7 As shown, after ablation, the central area of ​​the sample appears grayish-white.

[0119] The LAR and MAR experimental results of the aerogel composite are shown in Table 3. It can be seen that CPA... SiC-0 LAR compared to CPA 0-0 It decreased by 41.7%, CPA 0-ZrC LAR compared to CPA 0-0 It decreased by 22.2%, while CPA SiC-ZrC LAR compared to CPA 0-0 It decreased by 66.7%, which means it's comparable to the CPA.0-0 In contrast, CPA SiC-ZrC has a better LAR reduction effect than CPA SiC-0 and CPA 0-ZrC , and plays a synergistic role in ablative resistance.

[0120] The experimental results show that the oxidation resistance of the fiber felt can be effectively improved by coating the SiC-ZrC composite ceramic precursor, and the CPA SiC-ZrC ablative resistance is significantly improved.

[0121] Table 3 Ablation and mass ablation rate of aerogel composite

[0122]

[0123] The thermal protection performance is not only related to the ablation rate, but also related to the heat insulation capacity. Therefore, the surface temperature of different aerogel composites during the ablation process was measured by a high-temperature infrared thermal imager. The surface temperature change curve is shown in Figure 7 . It can be seen that the surface temperature of the sample rises rapidly after contacting the oxyacetylene flame, and can reach 1950℃ at the highest, and finally fluctuates around it. The metal probe was fixed on the back of the sample to measure the back temperature change, and the experimental results are shown in ​ a. After ablation for 70s, the back temperature of CPA 0-0 rose to 324℃, the back temperature of CPA SiC-0 was 229℃, the back temperature of CPA 0-ZrC was 216℃, and the back temperature of CPA SiC-ZrC only rose to 147℃, which was 177℃ lower than CPA 0-0 , and had a temperature difference of about 1800℃ from the surface temperature.

[0124] The experimental results show that CPA SiC-0 , CPA 0-ZrC and CPA SiC-ZrC have excellent heat insulation performance compared with CPA 0-0 , and CPA SiC-ZrC is the most excellent.

[0125] The present application provides an in-situ ceramic aerogel composite material with excellent thermal protection performance and its preparation method and application. The present application obtains a carbon fiber felt coated with a SiC-ZrC composite ceramic precursor layer by sequentially dipping and solidifying SiC ceramic precursor and ZrC ceramic precursor on the carbon fiber felt, and prepares a ceramic precursor coated carbon fiber felt reinforced silicon / phenolic hybrid aerogel composite material after compounding with organosilicon hybrid phenolic resin. The density of the aerogel composite material is 0.34g / cm 3 , which can meet the demand of TPS weight reduction of new spacecraft. The aerogel composite material CPASiC-ZrC Linear ablation rate compared with CPA 0-0 Decreased by 66.7%, with excellent ablation resistance; the back temperature of the aerogel composite is only 147 DEG C after working for 70s at 1950 DEG C, with excellent heat insulation performance in a harsh thermal environment. The experimental results show that the aerogel composite can be used as a candidate material for light TPS, and can be applied to difficult tasks such as deep space exploration, space-air return, near space long-time flight, etc.

Claims

1. A fibrous mat aerogel composite, characterized in that, Its raw materials include fiber felt coated with ceramic precursor and resin, wherein the ceramic precursor is SiC ceramic precursor and ZrC ceramic precursor; the SiC ceramic precursor is any one or more of polycarbosilane, SiC powder, polysiloxane and polysilazane. The fiber felt is carbon fiber felt; The resin is a phenolic resin, and the phenolic resin is an organosilicon hybrid phenolic resin; The organosilicon hybrid phenolic resin is prepared using AMPS, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, (3-aminopropyl)triethoxysilane and phenolic resin as raw materials. The AMPS was prepared from octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane and 1,3-bis(3-aminopropyl)tetramethyldisiloxane.

2. The fibrous felt aerogel composite of claim 1, wherein, The method for preparing the AMPS includes the following steps: Octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane and a catalyst are mixed, and an inert gas is introduced to react, thus obtaining the product.

3. The fibrous felt aerogel composite of claim 2, wherein, The catalyst is tetramethylammonium hydroxide; And / or, the reaction is carried out at 80~180℃ for 1~8h, and then the temperature is raised to 150~200℃ and held for 0.5~5h; The mass of the catalyst is 0.1% to 6% of the total mass of octaphenylcyclotetrasiloxane and octamethylcyclotetrasiloxane; The molar ratio of the octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane and 1,3-bis(3-aminopropyl)tetramethyldisiloxane is (0.5~5):(5~9.5):

2.

4. The fibrous felt aerogel composite of claim 3, wherein, The molar ratio of the octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, and 1,3-bis(3-aminopropyl)tetramethyldisiloxane is 1.5:8.5:

2.

5. The fibrous felt aerogel composite of claim 1, wherein, The molar ratio of the amino group in the AMPS to the anhydride in the 3,3',4,4'-biphenyltetracarboxylic acid dianhydride is 1:0.5~1.6; The (3-aminopropyl)triethoxysilane is 10% to 50% mol of amino content in AMPS.

6. The fibrous felt aerogel composite of claim 1, wherein, The organosilicon hybrid phenolic resin is prepared by the following method; (1) In a solvent, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and AMPS are mixed and reacted; (2) After adding (3-aminopropyl)triethoxysilane, the reaction was continued to obtain AMPSA; (3) React AMPSA with phenolic resin solution to obtain the product.

7. The fibrous felt aerogel composite of claim 6, wherein, In step (1), the solvent is tetrahydrofuran; And / or, in step (1), the reaction temperature is 20~80℃, the reaction time is 0.5~5h; the mass ratio of the solvent to AMPS is (1~5):1; And / or, in step (2), the temperature of the reaction is 20~80℃, and the reaction time is 0.5~5h; And / or, in step (3), the solvent of the phenolic resin solution is ethanol, wherein the mass ratio of phenolic resin to ethanol is (0.5-1):1, the reaction temperature is 50~110℃, and the reaction time is 0.5-2h.

8. The fibrous felt aerogel composite of claims 1-7, wherein, The method for preparing the fiber felt coated with the ceramic precursor includes the following steps: 1) dipping the fiber felt into a solution of SiC ceramic precursor, and then solidifying to obtain the fiber felt coated with SiC ceramic precursor; 2) dipping the fiber felt coated with SiC ceramic precursor obtained in step 1) into a solution of ZrC ceramic precursor, and then solidifying to obtain the fiber felt coated with ZrC ceramic precursor; or, a) dipping the fiber felt into a solution of ZrC ceramic precursor, and then solidifying to obtain the fiber felt coated with ZrC ceramic precursor; b) dipping the fiber felt coated with ZrC ceramic precursor obtained in step a) into a solution of SiC ceramic precursor, and then solidifying to obtain the fiber felt coated with SiC ceramic precursor.

9. The fibrous felt aerogel composite of claim 8, wherein, The solvent in the solution of SiC ceramic precursor or ZrC ceramic precursor is selected from any one or more than two of benzene, toluene, xylene, tetrahydrofuran, and ethylene glycol; The solidifying is carried out in an inert gas at 100-300℃ for 0.5-5h; The mass concentration of SiC ceramic precursor in the solution of SiC ceramic precursor is 0.1%-30%; The mass concentration of ZrC ceramic precursor in the solution of ZrC ceramic precursor is 0.1%-30%.

10. The fiber felt aerogel composite material according to claim 9, wherein The solidifying is carried out in nitrogen at 200℃ for 1h; The mass concentration of SiC ceramic precursor in the solution of SiC ceramic precursor is 3%; The mass concentration of ZrC ceramic precursor in the solution of ZrC ceramic precursor is 3%.

11. A method of making the fibrous felt aerogel composite of any one of claims 1-10, characterized in that, The method comprises the following steps: 1) mixing resin, organic solvent A, and curing agent to obtain a mixed solution, dipping the fiber felt coated with ceramic precursor into the mixed solution, and then performing sol-gel to obtain wet gel; 2) performing solvent replacement on the wet gel obtained in step 1) using organic solvent B to obtain the fiber felt aerogel composite material.

12. The method of claim 11, wherein, The organic solvent A is selected from any one of ethylene glycol, xylene, dimethyl sulfoxide, acetone, ethanol, and tetrahydrofuran; The organic solvent B is selected from ethanol, tetrahydrofuran, acetone, and toluene; the solvent A and solvent B are not the same; The curing agent is selected from any one or more than two of hexamethylenetetramine, thermosetting phenolic resin, and paraformaldehyde; The sol-gel is performed by sequentially maintaining at 90-150℃ for 0.5-5h, at 90-400℃ for 0.5-5h, and at 150-280℃ for 0.5-5h; The mass ratio of resin, organic solvent A, and curing agent in step 2) is (0.1-5):(0.1-10):(0.01-10).

13. The method of claim 12, wherein, The organic solvent A is ethylene glycol; the organic solvent B is ethanol; the curing agent is hexamethylenetetramine; the mass ratio of resin, organic solvent A, and curing agent in step 2) is 1:4:0.15; and the sol-gel is performed by sequentially maintaining at 120℃ for 2h, at 150℃ for 2h, and at 180℃ for 2h.

14. Use of the fiber felt aerogel composite material according to any one of claims 1-10 in the preparation of thermal protection materials.

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